With the growing concerns over environmental impacts and the every increasing cost of energy products, both producers and consumers of internal combustion engines are interested in means to improve the operational efficiency of these engines. One area receiving considerable attention is the use of energy recovery systems in road vehicles, commonly referred to as hybrids vehicles. These systems have mechanisms for capturing energy during braking, storing the captured energy and later consuming the energy to provide motive power to the vehicle. Typically these systems use a single electrical generator/motor or a single hydraulic pump/motor for capturing the energy and for providing motive power from the captured energy. The generator/motor or pump/motor is typically coupled to the drive-train of the vehicle via a transmission (e.g. a continuously variable transmission) or gear system (e.g. a planetary gear set) that is downstream from the prime mover (e.g. internal combustion engine). Motive power can be provided by the generator/motor or pump/motor in conjunction with motive power provided by the prime mover. When a multi-cylinder reciprocating-piston engine is used as the prime mover, the engine typically generates motive power that includes power pulses that correspond to the power generation sequence of the individual cylinders in the engine. The motive power provided by the generator/motor or pump/motor is not typically synchronized to the power pulses of the internal combustion engine and therefore does not contribute to smoothing out (i.e. mitigating) the power pulses. In some instances (especially in the case of a reciprocating pump/motor) additional asynchronous power pulses may be added to the total motive power flow.
What is needed is an energy recovery (i.e. regeneration) system for use with a reciprocating-piston engine that can provide motive power in a way that mitigates the power pulses intrinsic to the output of the engine.